1. Field of the Invention
This invention relates to a method of detecting a characteristic of a radar apparatus for a vehicle, a radar characteristic detection apparatus, and a recording medium recording the method of detecting a characteristic of a radar.
2. Description of the Prior Art
A radar characteristic detection apparatus that detects a deterioration degree in the characteristic of the radar apparatus is known. Japanese patent application provisional publication No. 11-109030 discloses such a radar apparatus. In this apparatus, the deterioration degree is detected by comparing the magnitude of the reflection wave detected by a load surface reflection wave detection means with a predetermined threshold value.
The aim of the present invention is to provide a superior radar apparatus for a vehicle, a superior radar characteristic detection apparatus, and a superior recording medium recording the method of detecting a characteristic of a radar.
According to the present invention, a first aspect of the present invention is a method of detecting a characteristic of a radar apparatus for a vehicle on the basis of data of an object obtained by said radar apparatus, said data including distance data of said object and a level of a radar signal reflected by said object and received by said radar apparatus, comprising the steps of: (a) repeatedly storing said distance data to said object and said level of said radar signal with relation therebetween; and (b) detecting said characteristic of said radar apparatus from variation in distribution of said repeatedly stored distance data and levels of said radar signal.
Preferably, the method as mentioned above, further comprises the step of: (c) detecting variation of said characteristic of said radar apparatus by comparing said distribution with a reference distribution. In this case, the steps of: effecting said steps (a) and (b); and storing said distribution as said reference distribution may be further included.
Moreover, the method may further comprise the step of: generating a control signal in accordance with said detected characteristic. Moreover, the method may be further comprise the steps of: detecting a peak level of spread spectrum and comparing said peak level with a threshold value to detect said object; detecting a relative speed of said object when said peak level is higher than said threshold value; determining whether said data of said object is subjected to said steps (a) and (b) in accordance with the result of said step of detecting said peak level.
According to the present invention, a second aspect of the present invention is a radar apparatus characteristic detection apparatus detecting a characteristic of a radar apparatus for a vehicle on the basis of data of an object obtained by said radar apparatus, said data including distance data of said object and a level of a radar signal reflected by said object and received by said radar apparatus, comprising: storing means for repeatedly storing said distance data and said level with relation therebetween; and detecting means for detecting said characteristic of said radar apparatus from variation in distribution of said repeatedly stored distance data and levels.
Preferably, the radar apparatus characteristic detection apparatus further comprises: variation detection means for detecting variation of said characteristic of said radar apparatus, wherein said variation detection means includes comparing means for comparing said distribution with a reference distribution. In this case, means for determining a characteristic curve in accordance with said distribution and said comparing means comparing said distribution with a reference characteristic curve may be further included. Moreover, approximating means for approximating said distribution to provide a liner equation may be further included. Moreover, calculation means for calculating an intercept of said linear equation and a reference intercept of a reference linear equation of said reference distribution may be further included, wherein said comparing means compares said intercept with said reference intercept.
Preferably, the radar apparatus characteristic detection apparatus further comprises: input means for inputting a signal from said vehicle. Moreover, the radar apparatus characteristic detection apparatus may further comprise: judging means for judging whether said variation of said characteristic of said radar apparatus is caused by the radar apparatus itself or an external reason in accordance with said signal inputted from said vehicle.
Preferably, the radar apparatus characteristic detection apparatus further comprise: judging means for judging that the object is moving in accordance with data from said radar and said storing means and said detection means are operated when said object is judged to be moving.
Preferably, the radar apparatus characteristic detection apparatus further comprises: recognizing means for recognizing said object in accordance with said data from said radar with a threshold value, and changing means for changing said threshold value when variation of said characteristic of said radar apparatus is detected.
Preferably, the radar apparatus characteristic detection apparatus further comprises: generating and outputting means for generating and outputting a mode control signal when said second detecting means detects said variation.
According to the present invention, a third aspect of the present invention is a recording medium for recording processing in detecting a characteristic of a radar apparatus for a vehicle on the basis of data of an object obtained by said radar apparatus, said data including distance data of said object and a level of a radar signal reflected by said object and received by said radar apparatus, said processing including the steps of: (a) repeatedly storing said distance data to said object and said level of said radar signal with relation therebetween; and (b) detecting said characteristic of said radar apparatus from variation in distribution of said repeatedly stored distance data and levels of said radar signal.
Preferably, in the recording medium, said processing further comprising the step of: (c) detecting variation of said characteristic of said radar apparatus by comparing said distribution with a reference distribution.